Roles of apelin/APJ system in cancer: Biomarker, predictor, and emerging therapeutic target

Abstract Cancer is a disease that seriously endangers human health and is mainly characterized by a high metastasis rate, a high recurrence rate, and a high mortality rate. The treatment of cancer has always been an important research direction of scientific research. A number of studies have shown that the apelin/APJ system is involved in the development and poor prognosis of a variety of cancers, such as lung cancer, liver cancer, cholangiocarcinoma, breast cancer, glioblastoma, prostate cancer, ovarian cancer, and so on. Accumulating evidence has also shown that the apelin/APJ system acts as a biomarker and predictor of postoperative effects in multiple cancers, which can also affect the tumor microenvironment and the efficacy of cancer immunotherapy. Considering that the apelin/APJ system may be a potential target for cancer treatment, it is of great significance for the study of new cancer treatment targets. To better understand the role of the apelin/APJ system on the occurrence and development of cancer, this article reviews the role of the apelin/APJ system in the occurrence and development of various cancers, angiogenesis, tumor stem cells, tumor microenvironment, drug resistance, poor prognosis, and the research progress of related anticancer drugs.